اثر هيپركسي نورموباريك متناوب و پيوسته بر ادم مغزي و نفوذپذيري سد خوني مغزي در مدل سكته مغزي رت

The effect of intermittent and prolonged normobaric hyperoxia on brain edema and blood brain barrier permeability in the rat brain stroke model

Ischemic preconditioning (IPC) is an endogenous phenomenon that can induces ischemic tolerance (IT) in many organs such as brain. Noxious stimuli under the threshold of cell injury induce adaptive responses that protect the brain against additional stress from the same (tolerance) or other (cross-tolerance) stimuli. In this study, we examined the intermittent and prolonged dose of normobaric hyperoxia (NBHO) on neurologic deficit scores, brain edema, and blood brain barrier (BBB) permeability after middle cerebral artery occlusion (MCAO). The rats were exposed with NBHO in prolonged (24h) and intermittent (4hx6days) groups. After 24 h, they were subjected to 60 minutes MCAO followed by 24h of reperfusion. Then, IT induced by intermittent and prolonged NBHO were measured by neurologic deficit scores, brain edema by weighting of ischemic and non-ischemic hemispheres in control, sham, and experimental groups, and BBB permeability by measurement of Evans Blue (EB) extravasations concentration of ischemia and non-ischemic hemispheres in control, sham, and experimental groups. The findings indicate that intermittent and prolonged NBHO are involved in the induction of IT. Pretreatment with prolonged and intermittent NBHO reduced neurologic deficit scores significantly whereas reduction of brain edema and EB extravasations in prolonged NBHO were not significantly. EB extravasations and brain edema were decreased in intermittent NBHO significantly. EB extravasations and brain edema were decreased in intermittent NBHO significantly. Intermittent NBHO has low toxicity and side effects. These results show that intermittent NBHO is more effective than prolonged NBHO on IT induction and can be used for clinical cases.